PHP Tutorial :: Reference (III)

Reference of PHP

PHP configuration directives

Allows functions such as file_get_contents() to work with URLs besides local paths

auto_append_file

Set it with a file name so that the PHP code written on that file will be executed after the PHP interpreter
executes a program. This allows for example to print a footer in the pages.

auto_prepend_file

Set it with a filename so that the PHP code written on that file will be executed before the PHP interpreter
executes a program. This allows to include functions or files that are used everywhere in the website.

browscap

Set it as the file name of a browser possibilities file.

display_errors

On for debugging, Off for production

When activated, the PHP interpreter prints errors as part of the result of PHP programs.

error_reporting

E_ALL

Controls which type of errors will be reported by the PHP interpreter.

extension

Each extension line in php.ini loads a PHP extension. The extension library must be present in the system
to load it.

extension_dir

The directory in which the PHP interpreter looks for the extensions specified by the directive extension.

file_uploads

On

Controls if it is allowed to send files via forms.

include_path

A list of directories in which the PHP interpreter looks for files that are loaded via include(), require(),
include_once() and require_once().

log_errors

On

When activated, the PHP interpreter places the program errors in the server's error log file.

magic_quotes_gpc

Off

When activated, the PHP interpreter automatically escapes form input data to prepare it for being
included in a SQL query. Not recommended because it unnecessarily adds slashes in any string that is not used
for a SQL query.

magic_quotes_runtime

Off

When activated, the PHP interpreter automatically escapes data read from an external file to prepare
it for being included in a SQL query. Not recommended because of forementioned reasons.

output_buffering

On

When activated, the PHP interpreter waits for its script to be executed before sending HTTP Request
and Response Headers, facilitating the usage of cookies and sessions.

register_globals

Off

When activated, the PHP interpreter creates individual variables for each form sent or URL variable.
For example, the global variable dinner would contain the value of the parameter "dinner" of the form sent.
Activating register_globals exposes the programs to many security risks.

session.auto_start

On (if sessions are used)

When activated, the PHP interpreter starts a session at the beginning of each webpage, so calling the
function session_start() would be unnecessary.

session.gc_maxlifetime

1440

The number of seconds that a session should last before expiring. The default value 1440 is good for most
applications.

session.gc_probability

1

The possibility (in percentage) that the expired sessions would be cleaned at the beginning of any request to
the server. The default value 1 is good for most applications.

SMTP

This directive is used only in Windows. It is the name of a SMTP host that should be used for sending messages
when calling the function mail().

short_open_tag

Off

When activated, a PHP block can be started with <? samely than with <?php. Since not every server is
configured to accept short opening tags, it is a good practice to deactivate this directive and avoid writing short
opening tags.

track_errors

On for debugging, Off for production

When activated, the PHP interpreter stores an error message in the global variable $php_errormsg when a
problem is encountered.

upload_max_filesize

2M

The maximum file size allowed for a file sent via form. Not recommended to increase this value unless it is
required.